Radioactive Sahara sand dust: “It comes back to us like a boomerang”

The images amazed many French people. Sand dust from the Sahara, carried by northward winds, flew over France on February 6, tinting the atmosphere yellow over much of the south and east of the country. This rise “is a phenomenon which occurs fairly regularly, provided that there is a fairly sustained southerly wind regime”, mainly in autumn or winter, Météo France explained at the time.

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According to the association for the control of radioactivity in the West (ACRO), this sand dust from the Sahara carried Cesium-137, residue from old French nuclear tests in the region at the beginning of the 1960s. of radiation protection at the University of Caen, Pierre Barbey is also a volunteer scientific advisor to the ACRO laboratory. With his association, he monitors “radioactivity” and tries to “act of vigilance”. He explains to L’Express the scope of his discovery, revealed on Friday at France 3 Bourgogne Franche-Comté.

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L’Express: Sahara sand dust collected in the Jura massif carried Cesium-137, residue from old French nuclear tests in the Sahara. How did you make this discovery?

Pierre Barbey: This issue of nuclear testing is well known to our association, which has been monitoring radioactivity in the environment for 35 years. We had already experienced a similar phenomenon thirty years ago in Normandy. The cars were covered with dust from Sahara sand. This radioactivity had been observed in soil deposits of these atmospheric particles.

This episode recurred in February. It is the consequence of the same meteorological phenomenon. In this region of the Sahara, hot air currents can carry the finest sand particles very far. This time, it went up on February 6 all over eastern France. I immediately understood that these sands came from the Sahara, I could observe the transformation of the atmosphere and the ocher-colored soils all day. The precedent of Normandy put the chip in my ear. In the evening, I took samples from my vehicle, which were analyzed at the Acro laboratory. The sand dust carried Cesium-137.

What is the scientific interest of this discovery?

The identification of Cesium-137 is final. This discovery is very interesting. These nuclear tests took place in the early 1960s. This shows the importance of this original nuclear pollution, both in space and in time. We are far from the Sahara, so a phenomenon of dilution and dispersion occurs. It is impressive to observe this radioactive pollution 60 years later. It comes back to us like a boomerang, because it is France’s responsibility to have launched these nuclear fires in the Sahara. It’s a return to sender.

In addition, these particles are deposited on the ground. It is pollution. It begins on soils, and then ends up on waterways. In mountainous regions, there will be phenomena of reconcentration of this radioactivity, because it will be transported by water and concentrated in low points.

Is the identification of Cesium-137 dangerous for humans?

It is a radioactive substance, therefore toxic. You have to see what is the exposure of people who are in the presence of such a cloud. They will inhale it – it’s internal contamination – and be exposed externally because Cesium-137 emits penetrating gamma radiation. Now the demonstrated Cesium-137 levels are extremely low. It will always be difficult to demonstrate a possible health effect. Even large-scale epidemiological studies – conducted in areas affected by the passage of the cloud of particles – could not possibly show health consequences.


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